For a stable street-hop, your motorcycle chain needs to hang in the sweet spot.
Too tight, and the tension will restrict your power and force, effectively hindering your motion (and safety). Too loose, though, and you risk a chain jumping off a sprocket; a slapping chain has the potential to damage moto-parts (and rider-parts).
In this article, we discuss symptoms of a loose motorcycle chain, the causes, and solutions.
1. Low Hanging Motorcycle Chain/Motorcycle Chain Out of Measurement
The earliest telltale sign of a loose chain is that it’s hanging low. If you suspect your chain is looser than it’s supposed to be, it probably is, but you should always measure to be sure.
Adjusting your bike chain is the quickest, most straightforward way to feel like an accomplished bike owner after reading your gas gauge and checking your tire pressure.
Here’s the philosophy: tighter than what your bike calls for is bad. Looser than what your bike calls for is bad.
See? You’re already killin’ it.
Don’t worry; I’ll tell you more. But before I do, this is a process you should be doing every 500 miles (805 km).
If you’re a flip-flopping dual-sport rider or a dirt biker, you should probably check more often.
On the other hand, if you’re on a belt-driven motorcycle, we’re glad you’re here, but this is about chains, and your situation is different, not in a bad way. We love all bikes equally, but these instructions pertain to chains.
And while you’re down there, check for kinks, clean your chain, and lube it up.
- Consult your owner’s manual to find the ideal chain tension/slack setting. Your bike may also have it on a sticker slapped onto its swingarm.
- Turn your motor off and put your bike in neutral, and lean it on its kickstand.
- The midway point is where the chain hangs the lowest, halfway between the front and rear sprocket. Find the midway point and push up on the bottom of the chain. Measure the distance between the lower, full-slack and the upper, no-slack positions, following the more bike-specific instructions and measurements outlined in your owner’s manual.
- Adjust the drive chain by loosening the axle nut three or so turns. You’ll need to put some torque on it to get it turning.
- On street bikes and some dirt bikes, there’ll be bolts you need to turn to adjust the chain. At the rate of just one-quarter turn per twist, adjust each side of the swingarm to the exact amount. Measure, adjust, measure, adjust, measure, stop when your chain is in the specified hanging distance outlined in the manual for your specific bike.
- Tighten the axle nut back to torque outlined in the owner’s manual.
I want to say this one more time to avoid any guilty feelings:
Too tight is just as bad as too loose; don’t over-tighten your chain.
2. Motorcycle Chain Tug
Another symptom of a loose chain on a motorcycle is a chain tug, a tugging feeling you feel when the bike keeps steady RPMs in a lower gear, which is another symptom of a loose chain.
Your chain is at its loosest in the bike’s lower gears, and chain tug is the adverse effect that the physics of a chain with excessive slack has on your momentum.
Chain tug generates a resisting force that pulls against your clutch. Sometimes, chain tug is so noticeable you’ll think your transmission is failing.
But no, lucky for you (I guess?), it’s probably just a loose chain tugging against your forward momentum.
Now that we’ve spent some time together, I feel comfortable saying that if you’re doing the work of properly maintaining your chain-driven motorcycle, a chain tug isn’t something you’ll ever experience.
Chain cleaning, lubricating, inspecting, measuring, and adjusting are routine moto-maintenance activities on a chain-driven motorcycle.
I know I already said this; not to sound like a squeaky chain, but you should be inspecting your bike chain every 500 miles and more often if you ride in the dirt.
Please also read our article about whether motorcycle engine braking is good or bad.
3. Motorcycle Chain Dislodges
A late and dangerous symptom of a loose chain that hasn’t been dealt with is a chain that dislodges itself from the sprockets or snags.
I’m no scientist, but I read a lot, and I owned a Triumph Bonnie at an age where I ignored things like chain tension. As in everything, what’s happening between your cogs and chain is energy transfer.
Grossly simplified, power is transferring from your pistons to your rear wheel via your chain. At an appropriate tension, that energy is transferred efficiently. On the other hand, a loose chain flails all over the place, spontaneously releasing the power your pistons intended for your tires.
In the process, the flailing chain can build up enough inertia to jump off your sprockets.
A slipped chain can not only cause damage to other moto-components in its vicinity as it ventures forth to slap out all its excess energy, but it could also hurt the rider.
That said, inspecting and maintaining your chain every 500 miles should catch a loose chain long before it has enough slack to jump off the cogs.
4 More Late Symptoms of a Loose Chain (Motorcyclists can avoid These Via Routine Chain Maintenance)
Here are four other late symptoms of a loose chain you can prevent with routine chain maintenance:
4. Grating new noises are happening as the chain runs over the sprockets.
5. When you open the throttle, the chain seems to make a clanging motion.
6. Chain rollers are missing.
7. O-rings are wearing off faster than usual.
Make sure to also read our article about things to check if motorcycle smells like gas.
Maintenance and Prevention
You can avoid most of the dramatic situations listed above by inspecting your chain regularly and tightening it to your bike’s manual spec.
Honestly, I’m not trying to scare you.
In fact, tightening a loosening chain on a motorcycle is relatively simple, even if you’re as inexperienced as I was when I had my Triumph.
That said, if you’re on a used bike, or if you’re just now starting to pay attention to the tension in your chain, and the chain is coming loose every time you ride, it might be easier to shell out the bread for a new chain and start your little maintenance routine from scratch on a freshie.
Dealing with a motorcycle chain that flops until it pops is annoying, but starting with a healthy chain and performing regular maintenance can make sure your chain never gets to that point.
Whether you fix your chain with the instructions in Section 1, or you’ve opted to start from scratch, affirm to pull a chain inspection every 500 miles from this point on.
When I was ripping around on that Bonnie back in the day, after I replaced the chain and got my bits together, a seasoned rider told me to check my chain tension every other time I got gas.
I didn’t always have a measuring tape on me, and we’ve already discussed how the chain tension on every bike is different, but that ballparks around a half-inch most of the time.
When doing a gas-pump chain-check, I’d eyeball it. If it seemed to be over a half-inch of play, I’d make a note to give it an official measurement when I got home (in those days, that meant consulting the owner’s manual I’d printed up at the library).
You want to clean your chain and hit it with lube every sixth month, or as soon as you hit 4,500 miles.
If you’re already down there changing the oil, give the chain some love too.
6 Reasons a Motorcycle Chain Comes Loose
Understanding the common reasons a motorcycle chain comes loose is an effective way to prevent your chain from slacking, tugging, and popping off your cogs.
Now that you understand the symptoms, dangers, and solutions to a loose chain, let’s cover the culprits behind a motorcycle chain that’s too loose.
The most common culprit behind a loose chain (common as in most of the time) is the rear axle that rolls between two fork-shaped components that point to the rear of the swingarm.
If the bolt-on on either side of the rear wheel is loose, your chain will loosen.
A new chain is bound to stretch a bit. Yes, metal expands when it gets hot, but there’s also some slack between the linkage that needs to release and set.
It works like this: the links rotate, rubbing into one another. As the links rub, friction creates a little “seat” for them to settle into against one another, and your chain will slack just a bit.
Check a new chain tension every 50 miles until you see it’s slacked. Once it does, it should be set. Tighten it to spec, and you should be good to go for the next 500 miles.
Also read our article about 4 things to check for motorcycle cold start problems.
Worn Chain Tensioner
Some bikes have what’s called a chain tensioner that automatically adjusts your chain tension while riding.
Your motorcycle connects to the rear wheel via the swingarm.
Your swingarm isn’t set in place, so a chain needs slack to adapt to the swingarm’s moving without snapping.
A chain tensioner slacks and tightens your chain in real-time to compensate for the swingarm’s movement.
Keeping your chain tensioner clean and lubricated ensures an appropriate automatic chain adjustment and a longer-lasting chain.
Chain tensioners wear out, eventually. So once your bike hits around 50,000 miles, it might be time to assess your chain tensioner’s lifespan.
Worn Sprocket Teeth
Worn sprocket teeth create space and a lack of friction, which combine to loosen your chain over time.
Over-tightening Your Chain
In a pure example of Yin-Yang philosophy, over-tightening the chain forces it to stretch itself out to function.
Eventually, an over-tightened chain slacks so much you can’t tighten it enough to stop it from slipping loose.
Poor Fitting Chain
Chains on motorcycles are not interchangeable. So if you shoehorned a chain from a different bike onto your bike, it probably wouldn’t fit right.
Again, this is about energy transfer, and your bike is designed to transfer power in a particular way.
Unfortunately, a poorly fitting chain alters the path on which that power travels, and eventually, force is going places it’s not meant to and causing damage to your chain in the process.